AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER Description Pin Assignments The AP5004 is a step-down switching regulator with PWM control and includes a reference voltage source, oscillation circuit, error amplifier, and an internal NMOS. (Top View ) AP5004 provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to vary the duty ratio linearly from 0% up to 90%. An enable function, an over-current protect function, and a short circuit protect function are built inside, and when OCP or SCP happens, the operation frequency will be reduced from 300 KHz to 50 KHz. Also, an internal compensation block has been designed in to minimize the external component count. With built-in power NMOS, a step-down switching regulator can easily be built by adding a coil, capacitors, and a diode. The combination of high efficiency, low standby current, high input voltage (32V), and high output current (2.5A)in a small SOP-8L package gives the AP5004 an unprecedented advantage in any high power system applications. EN FB 1 2 Vboost Output 3 AP5004 4 8 7 GND 6 Vcc 5 Vcc GND SOP-8L Applications • • • • Microprocessor Core Supply Networking Power Supply LCD MNT, TV Power Supply Telecom Power Supply Features • • • • • • • • • • • Input Voltage: 10V to 32V Adjustable Output Voltage from 0.8V to 6V Duty Ratio: 0% to 90% PWM control Oscillation Frequency: 300KHz typical Short Circuit Protect Frequency:50 KHz 2uA Maximum Standby Current Current Limit, Enable Function Thermal Shutdown Function Built-in Internal SW N-channel MOS SOP-8L: Available in “Green” Molding Compound (No Br, Sb) Lead Free Finish/ RoHS Compliant (Note 1) Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at http://www.diodes.com/products/lead_free.html. AP5004 Document number: DS31444 Rev. 5 - 2 1 of 11 www.diodes.com August 2010 © Diodes Incorporated AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER Typical Application Circuit C7 0.1uF U1 3 VIN 5 6 R5 100K 1 Vboost Output VCC FB AP5004 VCC GND EN GND 4 1 2 7 8 R1 685ohm D1 B340 R2 130ohm C2 220uF/63V VOUT = 5V L1-(WURTH 744132) 33uH 2 C1 100pF C4 C5 470uF/16V 0.1uF C3 0.1uF C6 0.1uF Note: V OUT = VFB x (1+R1/R2) R B = 100 ~ 300 ohm Notes: 2. Suggested DIODES Power Schottky P/N: PDS540 or B540C. Pin Descriptions Pin Name Pin # EN 1 FB Vboost Output VCC GND 2 3 4 5、6 7、8 Description H: Normal operation L: Step-down operation stopped Feedback pin High-side gate driver boost pin Switch output pin VCC GND pin AP5004 Document number: DS31444 Rev. 5 - 2 2 of 11 www.diodes.com August 2010 © Diodes Incorporated AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER Functional Block Diagram Output Vcc Oscillation Circuit Reference Voltage + PWM - Switched Control Circuit Driver - FB VL Thermal Shutdown VEN EN Vboost GND Absolute Maximum Ratings Symbol ESD HBM ESD MM VCC VFB VEN Vboost VOUTPUT TJ TST Parameter Human Body Model ESD Protection Machine Model ESD Protection VCC Pin Voltage VOUT Pin Voltage EN Pin Voltage Vboost Pin Voltage Switch Pin Voltage Operating Junction Temperature Range Storage Temperature Range Rating Unit 1.8 550 VSS - 0.3 to VSS + 35 VSS - 0.3 to VCC VSS - 0.3 to VCC + 0.3 VOUTPUT + 7V VSS - 0.3 to VCC + 0.3 -10 to +125 -40 to +150 KV V V V V V V o C o C Caution: The absolute maximum ratings are rated values exceeding which the product could suffer physical damage. These values must therefore not be exceeded under any conditions. Recommended Operating Conditions Symbol VIN IOUT TA Parameter Input Voltage Output Current Operating Ambient Temperature AP5004 Document number: DS31444 Rev. 5 - 2 3 of 11 www.diodes.com Min Max Unit 10 0 -10 32 2.5 85 V A o C August 2010 © Diodes Incorporated AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER Electrical Characteristics (VIN = 12V, TA=25°C, unless otherwise specified) Symbol Parameter VFB VIN ISTBY ∆VOUT/VOUT ∆VOUT/VOUT fOSC Feedback Voltage Input Voltage Standby Current Line Regulation Load Regulation Oscillation Frequency Frequency of Current Limit or Short Circuit Protect Maximum Duty Cycle Minimum Duty Cycle EN Pin Logic Input Threshold Voltage fOSC1 DC VIH VIL ISH ISL RDS(ON) ILIMIT η θJA θJC Notes: Conditions Min Typ. Max Unit VEN =0V VIN = 10V~32V IOUT = 0.1 to 2.5A Measure waveform at SW pin 0.780 10 240 0.8 2 ±1.0 1 300 0.820 32 ±1.5 1.5 360 V V µA %/V % KHz Measure waveform at SW pin - 50 - KHz 2.0 3.5 - 90 0 20 -10 80 90 0.8 120 - % % - 124 - o - 25 - o VFB =0.5V VFB =1.0V Regulator ON Regulator OFF EN Pin Input Leakage Current Internal MOSFET RDS(ON) Current Limit Efficiency VIN = 12V, VOUT = 5V, IOUT = 2.5A Thermal Resistance JunctionSOP-8L (Note 3) to-Ambient Thermal Resistance JunctionSOP-8L (Note 3) to-Case V µA µA mΩ A % C/W C/W 3. Test condition for SOP-8L: Device mounted on 2oz copper, minimum recommended pad layout, FR-4 PCB. AP5004 Document number: DS31444 Rev. 5 - 2 4 of 11 www.diodes.com August 2010 © Diodes Incorporated AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER Typical Performance Characteristics Line Regulation 1.2 1.5 1 1.2 Line Regulation(%) Load Regulation(%) Load Regulation 0.8 0.6 0.4 0.9 0.6 0.3 0.2 0 0 0 0 1 2 4 8 12 3 Iout(A) Frequency vs. Vin 16 Vin(V) 20 24 28 32 Iccq vs. Vin 330 7.45 Vout=5V;Iout=0.2A VFB=1V 7.4 Quiescent Current(mA) Frequency(KHz) 325 320 315 7.35 7.3 7.25 7.2 7.15 7.1 7.05 310 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 Vin(V) Vin(V) Istandby vs. Vin 0.15 VEN=0V Standby Current(uA) 0.12 0.09 0.06 0.03 0 0 5 10 15 20 25 30 35 Vin(V) AP5004 Document number: DS31444 Rev. 5 - 2 5 of 11 www.diodes.com August 2010 © Diodes Incorporated AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER Typical Performance Characteristics (Continued) Vout Ripple (Vcc= 12V, Vout= 5V, Iout= 0A, Vripple= 19.0mV) Vout Ripple (Vcc= 12V, Vout= 5V, Iout= 2.5A, Vripple= 35.0mV) Load Transient Response (Iout= 0.1~2.5A, Vin= 12V, Vout= 5V) Load Transient Response (Iout= 0.1~2.5A, Vin= 32V, Vout= 5V) AP5004 Document number: DS31444 Rev. 5 - 2 6 of 11 www.diodes.com August 2010 © Diodes Incorporated AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER Test Circuit OUTPUT Vcc A EN FB Vboost Oscillation open open A OUTPUT Vcc Vboost FB + open - GND Enable function test EN GND Feedback function test 33uH 0.1uF Vboost OUTPUT FB Vcc 530 ohm + - EN 220uF + GND 470uF - V 100 ohm Operation function test AP5004 Document number: DS31444 Rev. 5 - 2 7 of 11 www.diodes.com August 2010 © Diodes Incorporated AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER Functional Description PWM Control The AP5004 consists of DC/DC converters that employ a pulse-width modulation (PWM) system. The PWM controller is internally clocked by a fixed 300KHz oscillator. When used as a converter, the AP5004’s pulse width varies in a range from 0% to 90%, according to the load current. The ripple voltage produced by the switching can easily be removed through a filter because the switching frequency remains constant. Therefore, these converters provide a low-ripple power over broad ranges of input voltage and load current. Enable Control The Enable Control allows the output of the AP5004 to be turned ON or OFF. Connecting the Enable pin to GND or any voltage source lower than 0.8V will turn the output OFF. In the OFF state, the current drawn through the VCC input is approximately 2µA. Please note that the slew rate from ON to OFF must be >0.013v/µs to ensure proper operation. BOOST Capacitor This capacitor boosts the gate drive to the internal MOSFET above VIN to fully turn it ON thus minimizing conduction losses in the power switch to maintain high efficiency. The recommended value of the capacitor is 0.1µF. The capacitor must be connected from pin 3 to the switch output, pin 4. Feedback This is the input to a two-stage high gain amplifier, which drives the PWM controller. Two external resistors are required to set the DC output voltage. For stable operation of the power supply, it is important to prevent coupling of any inductor flux to the feedback input. Current Limit The current limit threshold is set by the internal circuit such that the minimum switching current is 3.5A. If the switching current exceeds the threshold, the output voltage will drop and the switching frequency will be reduced to 50KHz. Inductor Selection Most designs operate with inductors of 15µH to 33µH. The inductor value can be derived from the following equation: L= (VIN − VOUT )VOUT ΔIL × fosc × VIN Large value inductors will result in a lower ripple current where as small value inductors will result in high ripple currents. The inductor ripple current should be set to approximately 15% of the maximum load current 2.5A, ∆IL=0.375A. The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation (2A+0.19A). Input Capacitor Selection The input current to the step-down converter is discontinuous, and therefore an input capacitor C2 is required to supply the AC current to the step-down converter while maintaining the DC input voltage. A low ESR capacitor is required to keep the noise at the IC to a minimum. Its RMS current rating should be greater than approximately half of the DC load current. AP5004 Document number: DS31444 Rev. 5 - 2 8 of 11 www.diodes.com August 2010 © Diodes Incorporated AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER Functional Description (Continued) Output Capacitor Selection An output capacitor is required to maintain the DC output voltage. Low ESR capacitors are preferred to keep the output voltage ripple low. The characteristics of the output capacitor also affect the stability of the regulation control system. The ESR dominates the impedance at the switching frequency.The output ripple is calculated as: VRIPPLE ≅ ΔI × RESR Output Rectifier Diode The output rectifier diode supplies the current to the inductor when the high-side switch is OFF. To reduce losses due to the diode forward voltage and recovery times, use a Schottky rectifier. PCB Layout Guide The dual Output pin (4) and VSS pins (7 & 8) on the SOP-8L package are internally connected to die pad. If low TC & TJ or a large PD (Power Dissipation) is needed, the PCB layout should allow for maximum possible copper area exposure at the SW pins. Please also follow the steps below to reduce switching noise. 1. Connect C3 to VCC and VSS pin as closely as possible to get good power filter effect. 2. Connect ground side of the C2 & D1 as closely as possible. Typical PC Board Layout: Top Side Layout Guide AP5004 Document number: DS31444 Rev. 5 - 2 Bottom Side Layout Guide 9 of 11 www.diodes.com August 2010 © Diodes Incorporated AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER Ordering Information AP5004 S G - 13 Device Lead Free Packing S : SOP-8L G : Green 13 : Tape & Reel 13” Tape and Reel Quantity Part Number Suffix 2500/Tape & Reel -13 Packaging (Note 4) SOP-8L Package Code AP5004SG-13 Notes: Package S 4. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at http://www.diodes.com/datasheets/ap02001.pdf. Marking Information ( Top View ) 5 8 Logo G : Green YY : Year : 08, 09,10~ WW : Week : 01~52; 52 represents 52 and 53 week X : Internal Code AP5004 YY WW X X Part Number 1 4 0.254 0.10/0.20 3.85/3.95 5.90/6.10 Package Outline Dimensions (All Dimensions in mm) Gauge Plane Seating Plane 0.62/0.82 Detail "A" 7°~9° 0.15/0.25 1.30/1.50 1.75max. 0.35max. 45° 7°~9° Detail "A" 0°/8° 0.3/0.5 1.27typ 4.85/4.95 5.4 8x-0.60 8x-1.55 6x-1.27 Land Pattern Recommendation (Unit: mm) AP5004 Document number: DS31444 Rev. 5 - 2 10 of 11 www.diodes.com August 2010 © Diodes Incorporated AP5004 PWM CONTROL 2.5A STEP-DOWN CONVERTER IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). 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